Dike No. 3, extending from the Illinois shore 1,408 feet, and 8 feet high above low water, nearly completed.

Dike No. 4, extending from the Illinois shore 1,126 feet, mainly completed.

The dikes in progress will be completed during the present season, and when their influence is developed at low water, it is probable that another dike will be located and commenced to extend and secure the results obtained.

NEW WORKS PROPOSED.

Improvements at other points are contemplated during the present fiscal year to the extent of the means available, selecting the localities where the obstructions to navigation are most formidable. Following the general principle that the first step in the improvement at any locality is the collection into a single channel of the whole low-water discharge of the river, the work for this season will chiefly be confined at new points to the closing of island chutes. In my report for last year (page 450, Report of Chief of Engineers, 1873) I suggested that it would be advisable, on the score of economy, that the United States should own the principal working appliances which must be used. Experience of the past year has demonstrated this course to be a necessity to the efficient conduct of the work.

Having been compelled to purchase for use on the work a tow-boat, several barges, three pile-drivers, and the tools required in quarrying stone and handling material, it is the intention to use this equipment during the present year, and to make such addition thereto as may be required for the efficient prosecution of the work. The act approved June 23, 1874, providing only $185,000 applicable to the improvement of the river from the Missouri to the Ohio, the number of new points where work can be undertaken this year will be limited to two, namely, Turkey and Devil's Islands. These places are now the worst obstructions between St. Louis and Cairo. The present appropriation, it is hoped, will secure as decided an improvement at these points as has been gained at Horsetail Bar, where, though the works already projected are incomplete and others are yet to be located, the depth of water in the channel is considerably greater than was found at the same stage of water last year.

SURVEYS AND TRIANGULATION.

At the beginning of the fiscal year a party was in the field, in charge of Assistant Engineer I. D. McKown, and had carried the triangulation about thirty miles below St. Louis. The work continued until the latter part of October, when the triangulation was suspended for the season, and the party directed to make special surveys at Devil's, Liberty, and Turkey Islands, Horsetail Bar, and Twin Hollows. These special surveys were completed November 30, 1873, when the party was withdrawn from the field and the survey-boat Arkansas laid up.

The assistants were occupied during the winter in completing and making a projection of the triangulation, giving as the present result a skeleton map filled in with sketched topography, except where the special surveys afforded the detail.

The party was re-organized on the 1st of May, 1874, and at the close of the fiscal year had arrived within seven miles of the mouth of the Ohio.

A special survey was made during May and June, 1874, to determine

the facts, and to correctly connect the present and proposed wharf-line of the city of St. Louis with our surveys. Questions of considerable moment to the general interests of navigation and the exercise of the right of conservancy may be required on the part of the United States. The surveys are complete, and are being plotted in the office. It is deemed advisable to defer the discussion of the subject until the water affords an opportunity to make additional observations.

The surveys ordered during the present season, under the allotment of $10,000 from the appropriation, approved June 23, 1874, for surveys and estimates for the improvements recommended by the Senate Committee on Transportation-Routes to the Seaboard, will be of the character of detailed examination of points where obstructions to navigation are known to exist.

The necessity for a triangulation of the valley proper of the river was shown in the report of 1873. I would respectfully renew the recommendation of the appropriation of $50,000 for this purpose.

Estimates of the cost of completing the improvement of the Mississippi River between the Illinois and Ohio rivers cannot be given. The surveys of the present season will enable me to submit estimates of the cost of removing present obstructions to navigation, but such estimates cannot be expected to cover all that will be required to complete the improvement of a river subject to so many changes as is the Mississippi. The detailed surveys made during the past season enable me to approximately estimate the cost of works now required at several of the worst places on the river. To improve the navigation at the points where improvement is most urgently demanded,,and to carry on the works heretofore undertaken, will require, for the fiscal year 1875 and 1876, the sum of $600,000, the appropriation of which sum is recommended for the improvement of the Mississippi River between the mouths of the Illinois and Ohio Rivers, the distribution of the sum to be at the discretion of the Chief of Engineers.

I am indebted to Hon. John F. Long, surveyor of customs of the port of St. Louis, for certain statistics given in his letter of the 28th of July, 1874, accompanying and forming a part of this report.

Referring to the letter of Mr. Long, I would call attention to the increase of tonnage as conclusive refutation of the oft-repeated assertion that the tonnage on the Mississippi is diminishing, the total increase being 39.7 per cent. of the tonnage of 1870. The steamboat tonnage having increased from 71,489 in 1870 to 76,829 in 1874, or 7.4 per cent., and the barge tonnage during the same period increased from 25,634 to 58,860, or 129.6 per cent., shows that while steamboat tonnage is increasing, the growth of the barge interest is in a much greater ratio. The demand for cheap transportation is doubtless the cause of the ratio being so greatly in favor of barges; but the improvement of the navigation by the removal of dangerous obstructions during the last six years or more, has furnished the opportunity for the change, by rendering barge navigation safe.

The works now in progress and contemplated in the portion of the river under my charge will still further facilitate the cheapened transportation by removing the occasion of delays. Removing the causes of danger and delay, the result will be a safe and expeditious transportation, which is synonymous with cheap transportation.

It is impossible to state in detail what amount of commerce and navigation would be benefited by the completion of the above improvements. Suffice it to say that the whole Mississippi Valley would be greatly benefited thereby.

Financial statement.

Balance in Treasury of United States July 1, 1873:
On account of appropriation for improvement of Mississippi
River from the Missouri to the Meramec, approved June
10, 1872.....

On account of appropriation for improvement of Mississippi
River from the Missouri to the Ohio, approved March 3,
1873..

On account of appropriation for improvement of Mississippi River from the Missouri to the Meramec, approved June 10, 1872....

On account of appropriation for improvement of Mississippi River from the Missouri to the Ohio, approved March 3, 1873....

Amount appropriated for improvement of Mississippi River from the Ohio to the Illinois, by the act approved June 23, 1874, $200,000, less $15,000, to be expended between the Missouri and Illinois....

Amount allotted from appropriation, approved June 23, 1874, for surveys and estimates for the improvements recommended by the Senate Committee on Transportation-Routes to the Seaboard, &c., to be expended in the survey of that portion of the Mississippi route lying between the mouth of the Illinois River and the mouth of the Ohio River......

Amount expended during the fiscal year ending June 30,
On account of appropriation for improvement of Mississippi
River from the Missouri to the Meramec, approved June 10,
1872...

On account of appropriation for improvement of Mississippi
River from the Missouri to the Ohio, approved March 3,

1873

Amount available July 1, 1874:

On account of appropriation for improvement of Mississippi River from the Missouri to the Meramec, approved June 10, 1872.....

On account of appropriation for improvement of Mississippi River from the Missouri to the Ohio, approved March 3, 1873.....

On account of appropriation for improvement of Mississippi River from the Ohio to the Illinois, approved June 23, 1874. $200,000, less $15,000, to be expended between the Missouri and Illinois.

On account of allotment from appropriation, approved June 23, 1874, for surveys and estimates for the improvements recommended by the Senate Committee on TransportationRoutes to the Seaboard, &c., to be expended in the survey of that portion of the Mississippi route lying between the mouth of the Illinois River and the mouth of the Ohio River.....

Amount required for the fiscal year ending June 30, 1876, for improvement of the Mississippi River between the mouths of the Illinois and Ohio Rivers..

For triangulation of the valley of the Mississippi River between the mouths of the Illinois and Ohio Rivers.

Report of Mr. D. M. Currie, Assistant Engineer.

ST. LOUIS, MO., July 15, 1874.

SIR: I have the honor respectfully to submit the following report of progress made upon works for the improvement of the Mississippi River at Sawyer and Venice Bends during the fiscal year ending June 30, 1874:

The contract that was awarded to Thomas M. Hackett at the opening of bids in this

office on the 26th day of June, 1873, and of which the abstract was published in the report of the Chief of Engineers for that fiscal year, page 451, for the continuation of the work for improving the Mississippi River at Sawyer Bend under the allotment made for that purpose from the appropriation by act of Congress approved March 3, 1873, was duly entered into by him on the 16th of July following.

Surveys were made of that part of Sawyer Bend lying between the upper end of the works constructed last year and the mouth of the Gingrass Creek in the latter part of July and first part of August, to determine what, if any, changes were necessary to be made in the location of the works or details of the plans. The only change that was made was a slight revision of the location of the longitudinal retaining dike, to make it conform as nearly as possible to the contour of the river-bank, upon which the river had encroached about 30 feet since the surveys were made in August, 1872.

The plan followed in constructing the protecting works was the same as adopted in the construction of similar works at that point during the year ending June 30, 1873, namely, to build a longitudinal retaining dike parallel with the direction that it was intended to give to the bank below mean low-water, and connect this dike with the top of the bank by cross-dikes, built at such intervals as would protect the intervening bank against erosion.

The interval between the dikes that have been built is 120 feet, and, so far as can be seen at this time, they furnish all the protection desired, but if the same system of protection is continued on the remainder of Sawyer Bend, it will become necessary to determine anew the spaces that will be protected by the cross-dikes, because the current impinges against that part of the bank more directly. They vary directly as the product of the length of the dike into the natural cosine of the angle included between the axis of the impinging current and the bank.

- : the

To illustrate, let u= the space protected, x = the length of the cross-dike, y natural coşine of the angle included between the axis of the impinging current and the bank, and c = a constant whose value is equal to the space protected per unit of dike when the axis of the current is parallel to the bank.

Then uc x y. If we make y=1, the axis of the current becomes parallel to the bank, and the space protected varies as x. If we make y0, the expression e x y reduces to 0, which shows that when the axis of the current is perpendicular to the bank the spaces between the cross-dikes reduces to 0, and that the system of protection becomes a continuous revetment.

The formula u = c x y furnishes an easy method of determining the space that cross-dikes will protect when the value of c is known.

Mr. Thomas M. Hackett commenced work under his contract on the 21st of August, which was as early as was practicable to do so, on account of the high stage of water that prevailed prior to that date. Even then the water was too high for the dredge to open the trench deep enough for the reception of brush in the foundation of the longitudinal dike, which, according to the plan adopted, was necessary to be done before the construction of the dikes could be commenced; therefore, 'his operations were necessarily confined to removing a salient point of the bank that projected across the line of the longitudinal dike, near the upper end of the works constructed during the preceding year, while the water remained too high for the dredge to reach the bottom of the trench. It was evident that to enable one dredge to open sufficient length of trench during the season it would have to be pushed to its utmost capacity, and the contractor was permitted to run it night and day. It was unsafe to work all night, however, under a caving bank, and he was able to make only about 16 hours of actual work per day. The dredge with which he commenced work, the Sam Vansant, was hired from H. S. Brown, and completed its term of service on the 6th of September, and from that time to the 16th, when he purchased one, no work was done.

The water reached a stage sufficiently low to render it practicable to commence constructing dikes on the 18th of September, but the contractor was not ready to commence delivering brush and stone in the work until the 3d of October, and then not in such quantities as was desired or that would indicate that he would be able to accomplish any considerable amount of work before the approaching winter would close all our operations on the river for the season.

He was at that time dividing his time and means between this work and that at Horsetail Bar, and was thus trying to carry more work than his means justified. About that time, however, you relieved him from further responsibility of the work at Horsetail Bar, which enabled him to concentrate all of his means and energies here, and told beneficially upon the progress that he made with this work after the 15th of October.

The United States furnished him a pile-driver for the work done during October, one driver being used at both Sawyer and Venice Bends, but after that he was required to furnish one to work under his contract, because one driver could not drive piles fast enough to keep the work moving without interruption at both places.

The progress that was made with the work in the latter part of the season exceeded our most sanguine expectations. This was due more to the unusually fine weather for

working that prevailed in the latter part of November and first of December than to any special effort on the part of the contractor, who, though probably doing the best that he could under the circumstances, was so cramped in his movements for want of means that he could not prosecute the work with any great vigor, and frequently the dredge had to stop working because he was not able to furnish the materials necessary to follow up the opening of the trench with the construction of the longitudinal dike. The dredge was discharged on the 28th of November, and the last brush of the season placed and sunk on the 1st of December. The contractor continued delivering stone and constructing the longitudinal and cross dikes until the 15th of December, when the river rose to 15.5 feet above low-water and submerged his quarry. Before it fell again sufficiently for him to resume work, the navigation became so hazardous that it was found necessary to suspend for the season. Soon afterward he was paid the retained percentage and other dues on account of his contract, and relieved from its further responsibility. The result of the season's operations is: 2,520 feet of longitudinal dike built, as shown on accompanying map, (A B,) which, being added to that built during the preceding year, and that undertaken by the board of water-commissioners of the city of St. Louis, makes 5,445 feet of the two miles recommended by the board of engineer officers.

The following statement shows the cost of labor and materials used in constructing 2,520 feet of longitudinal dike:

Items and quantities.

1,2374 hours of actual work of dredge and crew.

6,498 linear feet of pile-timber...

124 piles driven 6 feet, (driver furnished by United States)..

1854 linear feet of piles driven in excess of 6 feet, (driver furnished by United States.)

120 piles driven 6 feet, (driver furnished by contractor)

6 linear feet of piles driven in excess of 6 feet, (driver furnished by contractor).

Bids were received and opened in this office on the 9th of July for furnishing and delivering materials, and doing all the work required for the improvement of the Mississippi River at Sawyer and Venice Bends under the unexpended balance of the appropriation for the improvement of the Mississippi River between the Missouri and the Meramec, made by act of Congress approved June 10, 1872, and the contract was awarded to Messrs. Martin Keary & Bros., they being the lowest bidders. They entered into contract on the 21st of the same month. No work was done under that contract, however, although it was in force until the 6th of October, when you found it necessary to annul it for non-fulfillment of its terms on the part of the contractors; after which the work at Sawyer and Venice Bends under that appropriation was carried on by hiring labor and purchasing materials in open market.

SAWYER BEND,

The work was commenced at Sawyer Bend on the 27th of October, and continued, with slight interruptions, until the close of the year, and consisted in completing and repairing the work done during the year ending June 30, 1873, and in building crossdikes for the protection of the bank, stone for which was obtained from quarries on the river, and transported on barges while navigation remained open, but after its close it was obtained from a quarry on Broadway in this city, and hauled on wagons to the work.

The results of the operations during the year are:

The works left unfinished at the close of the preceding year were completed; those that were damaged by high-water were repaired; and 21 cross-dikes were built for the protection of 2,520 linear feet of bank, shown on the accompanying map between the points marked A and B.

Protection by cross-dikes instead of by continuous revetment, was adopted on account of the satisfactory results obtained when they were tried as a temporary expedient, and has stood the test of two high-water seasons, proving itself a sufficient protection at a less cost.

The amount of money expended for labor and materials used in the construction of